How to Install a Bathtub Drain

An important task associated with the installation of a new built-in or freestanding bathtub involves installing the bathtub drain. Assuming the main drain plumbing is already in the appropriate location for your bathtub, this can be a do-it-yourself job. Here’s what you need to know about bathtub drain installation.

Drain Terminology

There’s more to a bathtub drain than meets the eye. You’re likely accustomed to seeing finished bathtubs with a drain stopper and an overflow opening. However, there’s quite a bit of hardware behind the scenes including various pipes, gaskets, cover plates, and flanges. Let’s start with drain terminology before getting into the details of drain installation.

Drain Stopper — Also called a tub stopper, the drain stopper is the piece that twists or drops into position to stop water from draining from the bathtub. Once lifted, the water flows through the drain stopper and into the drain pipes. Drain stoppers are available in several standard configurations such as push and pull, popups, toe touch, lift and twist, and flip-its.

Drain Flange — The drain stopper you see is part of a larger drain component called a drain flange. The drain flange is also known as the drain body or drain basket. It’s a short cylinder containing the stopper that threads into place into the drain shoe.

Drain Shoe— The drain shoe, which is installed underneath the bathtub floor, connects the drain flange to a “waste tee” connected to the overflow and drainage pipe.

Overflow Pipe — The overflow pipe leads up to the overflow opening, located near the top of the bathtub. Should you leave the water running in a stopped bathtub, once the water level rises to the level of the overflow opening, it will drain through the opening and down the overflow pipe into the main bathtub drain to prevent an overflow.

What You Need

You’ll need just a few items to install a bathtub drain including the drain hardware, a few tools and putty tape.

Bathtub drain assembly — For a completely new installation, you may need the entire drain assembly including the stopper, drain flange, drain shoe, waste tee, overflow pipe, overflow cover, and any associated parts like gaskets and screws. If replacing an existing bathtub drain, you’ll likely use the existing drain shoe, waste tee, and pipes. You may need a new gasket, though.

Tools — Assuming this is a new installation, you’ll need just a wrench and flathead screwdriver as well as a drain specific “smart dumbbell” or “drain key” tool for removing and installing the bathtub drain. The type you need depends on the type of drain flanges you will be removing and installing.

Supplies — Make sure to have some plumber’s putty on hand to seal the lip of the drain flange. You may also want to use masking tape to cover and protect the exposed bathtub surface surrounding the drain flange.

Bathtub Drain Installation Steps

Note: These instructions assume the pipes and drain shoe have already been installed.

If you must first remove an existing bathtub drain, start here:

Identify the existing drain flange type — Is it a lift and-twist stopper or a pop-up? If you know who manufactured it, search for the manufacturer’s removal instructions. If not, look up removal instructions for the drain type you have.

Use the appropriate drain removal tool — The instructions will likely recommend the appropriate drain removal tool. Drain dumbbells are commonly used to remove drains with cross bars while drain keys, which expand in 360 degrees, can be used to remove other drain types.

Follow the manufacturer’s instructions to remove the old drain.

Once the drain has been removed, it’s time to install the new bathtub drain:

Step 1: Clean and dry the area around the drain completely. You’ll want to be sure that any debris, build up, or old plumber’s putting is completely removed.

Step 2: Check the condition of the rubber gasket located underneath the bathtub. If an existing gasket is in place, is it in good condition? If not, or if it’s nonexistent, you’ll want to use the new one that came with your drain assembly or purchase a new gasket.

Step 3: To remove an existing gasket, gently pry it off with a flathead screwdriver. If an existing drain shoe is in place, take care not to misalign the drain shoe; otherwise, you’ll need to realign it.

Step 4: Install the new gasket by pushing it into place.

Step 5: Use your hands to roll a section of plumber’s putty into a roll that’s pencil sized in thickness and long enough to wrap around the drain flange. Place the putty roll underneath the drain flange’s lip, wrapping it completely around. Try not to use too much plumber’s putty as an overly thick roll will interfere with positioning the flange and may cause leaks. Only a small amount of putty should ooze out as the flange is screwed into position.

Step 6: Put the drain flange in the drain hole, slowly threading it into the first few threads of the drain shoe by hand. Make sure it’s threading properly and not cross threading.

Step 7: Use your smart dumbbell or drain key to twist the drain flange into the drain shoe until it’s tight. From there, use a wrench for 25 percent of a turn to fully tighten the flange. Use care here as over tightening could break the seal or crack the bathtub. Keep an eye on the gasket to make sure it has stayed in the correct position.

Step 8: It’s not unusual for plumber’s putty to appear around the edge or the flange after you’ve screwed it into position. Remove this with a putty knife.

Step 9: Install the bathtub stopper, following the instructions provided with your hardware and run a quick test to make sure that there are no leaks.

Step 10: Remove the old overflow cover and install the new one (if applicable). If you’re also changing the overflow cover, this job is usually a simple matter of unscrewing a screw or two, removing the cover, placing the new cover, and screwing it in.

That’s it; you’ve just installed a new bathtub drain. After cleaning up your project, your bathtub is ready for use. Enjoy!